package com.lightsaber.trade.as.rest.resources;

import javax.servlet.http.HttpServletRequest;

import org.hibernate.FlushMode;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.dao.DataAccessResourceFailureException;
import org.springframework.orm.hibernate3.SessionFactoryUtils;
import org.springframework.orm.hibernate3.SessionHolder;
import org.springframework.stereotype.Component;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springside.modules.utils.spring.SpringContextHolder;

@Component
public class OpenSessionInRestfulFilter {

    public static final String DEFAULT_SESSION_FACTORY_BEAN_NAME = "sessionFactory";

    private String sessionFactoryBeanName = DEFAULT_SESSION_FACTORY_BEAN_NAME;

    private boolean singleSession = true;

    private FlushMode flushMode = FlushMode.MANUAL;

    private final static Logger log = LoggerFactory.getLogger(OpenSessionInRestfulFilter.class);

    /**
     * Set the bean name of the SessionFactory to fetch from Spring's root
     * application context. Default is "sessionFactory".
     * 
     * @see #DEFAULT_SESSION_FACTORY_BEAN_NAME
     */
    public void setSessionFactoryBeanName(final String sessionFactoryBeanName) {
        this.sessionFactoryBeanName = sessionFactoryBeanName;
    }

    /**
     * Return the bean name of the SessionFactory to fetch from Spring's root
     * application context.
     */
    protected String getSessionFactoryBeanName() {
        return this.sessionFactoryBeanName;
    }

    /**
     * Set whether to use a single session for each request. Default is "true".
     * <p>
     * If set to "false", each data access operation or transaction will use its
     * own session (like without Open Session in View). Each of those sessions
     * will be registered for deferred close, though, actually processed at
     * request completion.
     * 
     * @see SessionFactoryUtils#initDeferredClose
     * @see SessionFactoryUtils#processDeferredClose
     */
    public void setSingleSession(final boolean singleSession) {
        this.singleSession = singleSession;
    }

    /**
     * Return whether to use a single session for each request.
     */
    protected boolean isSingleSession() {
        return this.singleSession;
    }

    /**
     * Specify the Hibernate FlushMode to apply to this filter's
     * {@link org.hibernate.Session}. Only applied in single session mode.
     * <p>
     * Can be populated with the corresponding constant name in XML bean
     * definitions: e.g. "AUTO".
     * <p>
     * The default is "MANUAL". Specify "AUTO" if you intend to use this filter
     * without service layer transactions.
     * 
     * @see org.hibernate.Session#setFlushMode
     * @see org.hibernate.FlushMode#MANUAL
     * @see org.hibernate.FlushMode#AUTO
     */
    public void setFlushMode(final FlushMode flushMode) {
        this.flushMode = flushMode;
    }

    /**
     * Return the Hibernate FlushMode that this filter applies to its
     * {@link org.hibernate.Session} (in single session mode).
     */
    protected FlushMode getFlushMode() {
        return this.flushMode;
    }

    public void doFilterInternal(final RestfulHppCore test, final String[] args) {

        SessionFactory sessionFactory = lookupSessionFactory();
        boolean participate = false;

        if (isSingleSession()) {
            // single session mode
            if (TransactionSynchronizationManager.hasResource(sessionFactory)) {
                // Do not modify the Session: just set the participate flag.
                participate = true;
            } else {
                log.debug("Opening single Hibernate Session in OpenSessionInJobFilter");
                Session session = getSession(sessionFactory);
                TransactionSynchronizationManager.bindResource(sessionFactory, new SessionHolder(
                        session));
            }
        } else {
            // deferred close mode
            if (SessionFactoryUtils.isDeferredCloseActive(sessionFactory)) {
                // Do not modify deferred close: just set the participate flag.
                participate = true;
            } else {
                SessionFactoryUtils.initDeferredClose(sessionFactory);
            }
        }

        try {
            test.doExecute(sessionFactory, args);
        }

        finally {
            if (!participate) {
                if (isSingleSession()) {
                    // single session mode
                    SessionHolder sessionHolder = (SessionHolder) TransactionSynchronizationManager
                            .unbindResource(sessionFactory);
                    log.debug("Closing single Hibernate Session in OpenSessionInJobFilter");
                    closeSession(sessionHolder.getSession(), sessionFactory);
                } else {
                    // deferred close mode
                    SessionFactoryUtils.processDeferredClose(sessionFactory);
                }
            }
        }
    }

    /**
     * Look up the SessionFactory that this filter should use, taking the
     * current HTTP request as argument.
     * <p>
     * The default implementation delegates to the
     * {@link #lookupSessionFactory()} variant without arguments.
     * 
     * @param request
     *            the current request
     * @return the SessionFactory to use
     */
    protected SessionFactory lookupSessionFactory(final HttpServletRequest request) {
        return lookupSessionFactory();
    }

    /**
     * Look up the SessionFactory that this filter should use.
     * <p>
     * The default implementation looks for a bean with the specified name in
     * Spring's root application context.
     * 
     * @return the SessionFactory to use
     * @see #getSessionFactoryBeanName
     */
    protected SessionFactory lookupSessionFactory() {
        if (log.isDebugEnabled()) {
            log.debug("Using SessionFactory '" + getSessionFactoryBeanName()
                    + "' for OpenSessionInJobFilter");
        }

        return SpringContextHolder.getBean(SessionFactory.class);
    }

    /**
     * Get a Session for the SessionFactory that this filter uses. Note that
     * this just applies in single session mode!
     * <p>
     * The default implementation delegates to the
     * <code>SessionFactoryUtils.getSession</code> method and sets the
     * <code>Session</code>'s flush mode to "MANUAL".
     * <p>
     * Can be overridden in subclasses for creating a Session with a custom
     * entity interceptor or JDBC exception translator.
     * 
     * @param sessionFactory
     *            the SessionFactory that this filter uses
     * @return the Session to use
     * @throws DataAccessResourceFailureException
     *             if the Session could not be created
     * @see org.springframework.orm.hibernate3.SessionFactoryUtils#getSession(SessionFactory,
     *      boolean)
     * @see org.hibernate.FlushMode#MANUAL
     */
    protected Session getSession(final SessionFactory sessionFactory)
            throws DataAccessResourceFailureException {
        Session session = SessionFactoryUtils.getSession(sessionFactory, true);
        FlushMode flushMode = getFlushMode();
        if (flushMode != null) {
            session.setFlushMode(flushMode);
        }
        return session;
    }

    /**
     * Close the given Session. Note that this just applies in single session
     * mode!
     * <p>
     * Can be overridden in subclasses, e.g. for flushing the Session before
     * closing it. See class-level javadoc for a discussion of flush handling.
     * Note that you should also override getSession accordingly, to set the
     * flush mode to something else than NEVER.
     * 
     * @param session
     *            the Session used for filtering
     * @param sessionFactory
     *            the SessionFactory that this filter uses
     */
    protected void closeSession(final Session session, final SessionFactory sessionFactory) {
        SessionFactoryUtils.closeSession(session);
    }

}
